﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace OnlineManagement.Common
{
   public class ValidationCode
    {

        /// <summary>
        /// 生成验证码字符串
        /// </summary>
        /// <param name="codeLen">验证码字符长度</param>
        /// <returns>返回验证码字符串</returns>
        public static string MakeCode(int codeLen)
        {
            if (codeLen < 1)
            {
                return string.Empty;
            }
            int number;
            string checkCode = string.Empty;
            Random random = new Random();
            for (int index = 0; index < codeLen; index++)
            {
                number = random.Next();
                if (number % 2 == 0)
                {
                    checkCode += (char)('0' + (char)(number % 10)); //生成数字
                }
                else
                {
                    checkCode += (char)('A' + (char)(number % 26)); //生成字母
                }
            }
            return checkCode;
        }

        ///<summary>
        /// 获取验证码图片流
        /// </summary>
        /// <param name="checkCode">验证码字符串</param>
        /// <returns>返回验证码图片流</returns>
        public static MemoryStream CreateCodeImg(string checkCode)
        {
            if (string.IsNullOrEmpty(checkCode))
            {
                return null;
            }
            Bitmap image = new Bitmap(70, 30);
            using (Graphics graphic = Graphics.FromImage(image))
            {
                Random random = new Random();
                graphic.Clear(Color.White);
                for (int index = 0; index < 25; index++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    graphic.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                                                                    Color.Red, Color.DarkRed, 1.2f, true);
                graphic.DrawString(checkCode, font, brush, 2, 2);
                int x = 0;
                int y = 0;
                //画图片的前景噪音点
                for (int i = 0; i < 100; i++)
                {
                    x = random.Next(image.Width);
                    y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                graphic.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //将图片验证码保存为流Stream返回
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                return ms;
            }
        }
    }
}
